Statistical occurrence and mechanisms of the 2014–2016 delayed super El Niño captured by a...
Thual, Sulian; Majda, Andrew; Chen, Nan
2018-06-02 00:00:00
The recent 2014–2016 period was marked by a failed El Niño favoring a subsequent extreme El Niño with dramatic world- wide impacts. Here this new type of major event so-called the delayed super El Niño is realistically captured by a simple dynamical model for the equatorial Pacific with emphasis on the role of state-dependent stochastic wind bursts. We analyze qualitative analogues for this event compared and contrasted with the 1997–1998 super El Niño in ensemble experiments based on the simple model. In agreement with recent studies, the timing and intensity of such an event is strongly controlled by atmospheric wind bursts, both easterly and westerly. In particular, the early stalling by easterly wind bursts and subsequent development by westerly wind bursts as observed during 2014–2016 is consistently retrieved. We show in addition that individual wind bursts may control the main characteristics of the event only during its early development while sequences of consecutive wind bursts have more important cumulative effects. Another important result from the present analysis is the significant statistical occurence of the delayed super El Niño (around 20–30%) compared with the one of directly formed super events as that of 1997–1998. Such a high occurence is directly
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Abstract

The recent 2014–2016 period was marked by a failed El Niño favoring a subsequent extreme El Niño with dramatic world- wide impacts. Here this new type of major event so-called the delayed super El Niño is realistically captured by a simple dynamical model for the equatorial Pacific with emphasis on the role of state-dependent stochastic wind bursts. We analyze qualitative analogues for this event compared and contrasted with the 1997–1998 super El Niño in ensemble experiments based on the simple model. In agreement with recent studies, the timing and intensity of such an event is strongly controlled by atmospheric wind bursts, both easterly and westerly. In particular, the early stalling by easterly wind bursts and subsequent development by westerly wind bursts as observed during 2014–2016 is consistently retrieved. We show in addition that individual wind bursts may control the main characteristics of the event only during its early development while sequences of consecutive wind bursts have more important cumulative effects. Another important result from the present analysis is the significant statistical occurence of the delayed super El Niño (around 20–30%) compared with the one of directly formed super events as that of 1997–1998. Such a high occurence is directly

Journal

Climate Dynamics
– Springer Journals

Published: Jun 2, 2018

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References

An improved coupled model for ENSO prediction and implications for ocean initialization. Part I: The ocean data assimilation system